Midea MHC-V16W/D2RN8-B - Pb Troubleshooting

M thermal Mono
102 200204
Midea M thermal Mono Service Manual
4.23 Pb Troubleshooting
Digital display output
Description
 Water side heat exchanger anti-freeze protection.
 M thermal Mono stops running.
 Error code is displayed on refrigerant system main control board for refrigerant system and ANTI.FREEZE icon is
displayed on user interface.
Possible causes
 Normal system protection.
 Temperature sensor not connected properly or has malfunctioned.
 Hydronic system main PCB damaged.
Procedure
Pb
Outdoor ambient temperature is lower
than 4°C
Yes
Normal system protection. The system
will resume automatically
1
No
Water side heat exchanger water outlet
temperature sensor, water inlet
temperature sensor or backup electric
heater outlet water temperature sensor
loose
2
Yes
Ensure the temperature sensor is
connected properly
No
Water side heat exchanger water outlet
temperature sensor, water inlet
temperature sensor or backup electric
heater outlet water temperature sensor
has short-circuited or failed
3
Yes
Replace the temperature sensor
No
Replace outdoor main PCB
Notes:
1. Refer to Part 3, 5.7 “Water Side Heat Exchanger Anti-freeze Protection Control”.
2. Backup electric heater water outlet temperature sensor, water side heat exchanger water inlet temperature sensor and water side heat exchanger water
outlet temperature sensor connections are port CN6 on the hydronic system main PCB (labeled 8 in Figure 4-2.1 in Part 4, 2.2 “Main PCB for Hydronic
System”).
3. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor’s resistance
characteristics table, the sensor has failed. Refer to Part 2, 1 “Layout of Functional Components” and to Table 4-5.3 in Part 4, 5.1 “Temperature Sensor
Resistance Characteristics”.
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